THE MINERAL DESCLOIZITE

  • Chemistry: PbZn(VO4)(OH) , Lead Zinc Vanadate Hydroxide
  • Class: Phosphates
  • Group: Descloizite
  • Uses: As a minor ore of lead and zinc and as mineral specimens
  • Specimens
Descloizite is the namesake of the descloizite group of minerals. The group is composed of rather rare members of which descloizite is its most common member. Descloizite is an end member of a series composed of the mineral mottramite. Mottramite is the copper rich end member while descloizite is the zinc rich member. Both minerals usually contain significant percentages of both elements and are rarely pure. Descloizite can form nice well shaped crystals that have a nice luster and striking color. Its rarity and attractiveness are the reason for the typically high prices one would expect to pay for a fine specimen.

PHYSICAL CHARACTERISTICS:

  • Color is typically brown to reddish brown to black also yellow to orange with increase in copper content.
  • Luster is greasy.
  • Transparency: Crystals are transparent to opaque.
  • Crystal System is orthorhombic; 2/m2/m2/m
  • Crystal Habit is typically in small, flat platelets that have a rounded triangular shape or in a pyramidal form, also in tiny druzy crusts and stalactitic masses.
  • Cleavage is none.
  • Fracture is conchoidal to uneven.
  • Hardness is 3 to 3.5.
  • Specific Gravity is approximately 6.2 (very heavy for translucent minerals)
  • Streak is brownish red to orange to yellow.
  • Associated Minerals are wulfenite, vanadinite, mottramite, pyromorphite, and cerussite.
  • Other Characteristics: Some crystals can appear arrowhead shaped.
  • Notable Occurrences include Tsumeb, Nambia; Zambia; Germany; Pinal County, Arizona, and Grant County, New Mexico; U.S.A.
  • Best Field Indicators are color, crystal habit, localities and density.
DESCLOIZITE specimens:
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DESCLOIZITE specimen des-2
$ 30.00
Dims: 2.0" x 1.6" x 1.6"(5.1 x 4.1 x 4.1 cm)
Wt: 4.69 oz.(133.0 g)
Berg Aukew, Republic of South Africa
Large, well-developed crystals of Descloizite make up the bulk of this specimen. The crystals are a dark brown color, dimly transparent, and have a vitreous luster. Though they are quite large(0.2 - 1.5 cm long), they occur in sprays, as if they have radiating tendencies. The crystals occur in long, thin blades that look like spearheads. There are a few spots of noticeable damage to crystals in the cluster, but the vast majority are undamaged and in excellent condition. There is very little host rock, and it is pale brown in color and chalky in consistency.
no photo
des-2 ($ 30.00)
Berg Aukew, Republic of South Africa
DESCLOIZITE specimen des-3
$ 70.00
Dims: 2.5" x 2.0" x 1.5"(6.4 x 5.1 x 3.8 cm)
Wt: 5.06 oz.(143.5 g)
Tsumeb, Namibia
At least 20 large orthorombic tabular "spearhead" crystals of Descloizite are clustered together on this specimen. They have excellent form, and though there are several crystals that show damage, it is in generally good condition The largest crystal measures 1.0 x 0.5 x 0.3"(2.5 x 1.3 x 0.8 cm), and many others are almost as large. Countless tiny crystals at their bases are tightly packed to form a crust. All have a dark brown color, a pearly to waxy luster, and are only translucent at their edges. There is a thin layer of material coating the underside of the specimen that may be the remnants of a sandstone base, but it seems to meld very well with the crust, and is not very crumbly. These are some of the largest Descloizite crystals that I have come across.
no photo
des-3 ($ 70.00)
Tsumeb, Namibia
DESCLOIZITE specimen des-4
$ 70.00
Dims: 2.1" x 1.5" x 1.3"(5.3 x 3.8 x 3.3 cm)
Wt: 2.58 oz.(73.2 g)
Tsumeb, Namibia
Apart from one broken crystal and a few damaged ones near the specimen's edge, this Descloizite piece is in great condition. The crystals have a dark brown color, a pearly to vitreous luster, and are dimly translucent. They reach maximum dimensions of 1 x 0.5 x 0.1"(2.5 x 1.8 x 0.3 mm), and compressed into flowery aggregates of spearhead-shaped blades. They rest on a crust that is made up of tiny, intergrown Descloizites that are compacted together, and there is a thin layer of a sandy, light brown substance coating the underside of the crust. It is an impressive little specimen, with rather large crystals.
no photo
des-4 ($ 70.00)
Tsumeb, Namibia
DESCLOIZITE specimen des-5
$ 75.00
Dims: 2.1" x 1.7" x 0.9"(5.3 x 4.3 x 2.3 cm)
Wt: 1.61 oz.(45.7 g)
Berg Aukus, Namibia
The Descloizite crystals on this specimen have a rather bizarre aspect to their form. They range in size from less than 2 mm in all dimensions to 0.7 x 0.4 x 0.2"(1.8 x 1.0 x 0.5 cm), and occur in a commonly-seen orthorombic tabular "spearhead" shape. However, each basal termination edge is distended beyond the width of the crystal by at least 100%, creating odd shapes. The crystals range in color from a deep golden-brown to black with respect to size, from smallest to largest, as does their luster, which ranges from dull to submetallic. All crystals are opaque, but show some small patches of dim translucence. The smallest crystals are tightly intergrown to form the crust that all grow out of. The weird form of the larger crystals makes the piece very attractive to me.
no photo
des-5 ($ 75.00)
Berg Aukus, Namibia
DESCLOIZITE specimen des-6
$ 25.00
Dims: 1.1 x 0.5 x 0.2" (2.8 x 1.3 x 0.5 cm)
Wt: 12.7 g w/box
Berg Aukus, South West Africa
This thumbnail specimen consists of several small Descloizite crystals that are partly intergrown with a much larger crystal. The large crystal makes up almost all of the mass and volume of the piece, and is in good condition, showing light damage. Its orthorhombic bladed form is quite warped but still defined, and it has a dark brown color and a rather odd, dull, silky luster, though small areas show an adamantine brightness. It is affixed inside a plastic specimen box.
no photo
des-6 ($ 25.00)
Berg Aukus, South West Africa
DESCLOIZITE specimen des-7
$ 63.00
Dims: 4.1 x 2.8 x 1.0" (10.5 x 7.1 x 2.6 cm)
Wt: 4.7 oz. (134 g)
Commercial Incline, Georgetown District, Grant County, New Mexico, U.S.A.
This cabinet piece consists of a calcite base on which rests a crust of intergrown Descloizite clusters. These clusters are made up of small botryoidal formations, and each botryoidal orb does not exceed 1 mm in diameter. Though a few small formations seem to be nearly arborescent, there are not any formations that are more crystalline in appearance. The crust is generally in very good condition and its color ranges from pale orange to deep red-orange. Their luster is waxy and all are translucent at best, and more likely opaque. They rest on a bed of intergrown calcite that shows definite crystal form - a few hexagonal, basal faces are plainly visible.
no photo
des-7 ($ 63.00)
Commercial Incline, Georgetown District, Grant County, New Mexico, U.S.A.
DESCLOIZITE specimen des-8
$ 45.00
Dims: 4.2 x 3.3 x 0.8" (10.6 x 8.4 x 2.0 cm)
Wt: 2.0 oz. (57 g)
Chalk Mountain, Churchill County, Nevada, U.S.A.
A very thin, calcareous crust that is coated with microcrystalline Descloizite makes up this cabinet piece. The Descloizite is in very good condition, showing only light damage at its most exposed points, and takes on the form of countless tiny botryoidal orbs that each do not exceed 1 mm in diameter. All have a pale orange color and a matte luster and are completely opaque. The material has a nearly sandy texture that is easily visible- a large portion of the Descloizite crust shows no form whatsoever, and looks like sand that was blown into a drift. The calcite crust that acts as a host is essentially massive in form and very thin, and is thus quite fragile.
no photo
des-8 ($ 45.00)
Chalk Mountain, Churchill County, Nevada, U.S.A.
DESCLOIZITE specimen des-9
$ 45.00
Dims:2.5x1.7x1.2" (6.4x4.3x3.0 cm)
Wt: 2.5oz. (71g)
Commercial Mine, Georgetown, Grant cty., New Mexico
The matrix of this specimen is covered with tiny crystals of descloizite, ranging in color from a yellowish-orange to a reddish-orange. These crystals are too small to permit effective study. Still, it is quite fascinating to examine under a loupe. There is only minor damage on one side of this specimen.
no photo
des-9 ($ 45.00)
Commercial Mine, Georgetown, Grant cty., New Mexico
DESCLOIZITE specimen des-10
$ 75.00
Dims:3.7x2.6x2.5" (9.4x6.6x6.4 cm)
Wt: 11.7oz. (332g)
Berg Aukus Mine, S.W. Africa
This is one of the best cabinet descloizite specimens I have seen. Hundreds of dark, lustrous, tabular crystals of descloizite cover the light-colored host material. Some of these crystals have grown to just under 0.2" (0.5cm) in size, and are faintly translucent when held up to a bright light and examined with a loupe. There is only minor damage to this specimen.
no photo
des-10 ($ 75.00)
Berg Aukus Mine, S.W. Africa
DESCLOIZITE specimen des-11
$ 210.00
Dims: 6.2x4.4x3.0" (15.8x11.2x7.6 cm)
Wt: about 3 lbs. (1.35kg)
C&B Mine, Gila County, Arizona, USA
What appears to be druzy black quartz crystals on this cabinet specimen is actually a druze of transparent brown descloizite platelets. Only where the crystals are somewhat isolated against the white base rock is the brown color apparent to the naked eye. Under a loupe, the color and individual crystals in the "black" areas resolve to a deep brown and still transparent appearance. There is also a scattering of small calcite crystals, which in some places form a coating over the descloizite. Elsewhere, the descloizite sparkles very nicely.
no photo
des-11 ($210.00)
C&B Mine, Gila County, Arizona, USA
DESCLOIZITE specimen des-12
$ 75.00
Dims: 2.1x1.6x1.3" (5.3x4.2x3.3 cm)
Wt: 2.9 oz. (81.2g)
Berg Aukas, Namibia
This descloisite specimen is very nice. It is relatively pure, revealing its high density, and the crystals are in books of rounded triangles, a characteristic form. These clusters radiate from a small base of microcrystaline (almost massive) descloisite. Their color spans the typical range of reddish-brown to black, the crystals are dimly translucent (even the black tips transmit brown light), and they have a nice sparkle, almost like they were covered by a quartz druse.
no photo
des-12 ($ 75.00)
Berg Aukas, Namibia
 

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